How to charge your electric car with solar panels

Solar panels generate free, clean electricity – so naturally, you’ll want to use it to power everything in your life.

Charging your electric vehicle with solar electricity can save you hundreds of pounds, slash your carbon footprint, and reduce your dependence on public charging stations and the grid.

In this guide, we’ll explain how using solar panels to charge an electric car works, what the best setup is, how much it costs upfront, and how much you can save.

If you would like to see the savings you could get from a solar & battery system, answer a few questions below and we’ll provide an estimate.

How does it work?

If you buy an EV charger that isn’t fully compatible with solar panels, it will still use the electricity your panels generate, either while it’s being produced or from your solar battery, if you have one.

However, you won’t be able to control what source your charger uses; it’ll simply draw electricity from wherever it can.

That means it’ll probably use some grid electricity if you charge your car during the day, to meet the peak power rating of your EV charger.

You could also buy a technologically advanced ‘solar charger,’ which allows you to charge your car with solar electricity more effectively, with more options.

These chargers usually come with a CT (Current Transformer) clamp that automatically turns the charger on when it senses your solar panels are generating electricity.

The rest of the time, your charger either won’t fill your car’s battery at all, or will do so using grid electricity – but relatively slowly.

When compared to a regular EV charger, a solar charger can significantly increase how much of your solar electricity you use to charge your car.

This will allow you to cut your electricity bills, and ensure your EV is always sufficiently charged.

Do you need a battery as well?

A storage battery helps with EV charging by storing solar electricity so you can use it to charge your car after the sun goes down.

Without a storage battery, your solar panels can only charge your EV when they’re producing electricity, during the day.

And if your solar panel system produces a lower output than your EV charger – for instance, if it’s a 4kWp (kilowatt-peak) array powering a 7kW charger – you’ll still use some grid electricity alongside your solar energy.

And you won’t be able to use any solar electricity in this process if your car’s not usually home when the sun’s up – which is the case for at least some of the year if, for instance, you’re among the 68% of Brits who drive to work.

If you wait until the sun’s gone down, your home charger can only use grid electricity to fill up your EV – a process that typically costs around £490 per year, according to our calculations – instead of free solar electricity.

The only way to effectively use solar panels to charge an electric car that’s not home during the day is by using them alongside a storage battery.

What are the best EV chargers for solar charging?

These are the best electric car chargers for solar charging, because they’re designed to be compatible with solar panel systems.

Most chargers aren’t designed in this way. They can still use the electricity your solar panels produce, but you won’t be able to choose how much solar electricity they use.

Fortunately, at this stage in their technological development, it’s relatively easy to find solar-compatible EV chargers.

Here’s a rundown of all the models that are optimised to use solar-generated electricity.

What are the advantages of charging your EV with solar?

There are several pros – and not many cons – of charging an electric car with solar panels.

After all, once you’ve bought the system and charger, you can generate free, clean electricity to run your car.

This can save you hundreds of pounds per year, reduce your carbon footprint, and protect you against rising energy prices – plus you can use the additional electricity your panels produce to power your home.

1. Save money on charging
2. Maximise your savings with smart tariffs
3. Cut your carbon footprint
4. Protect yourself against energy price rises

To find out how much a solar & battery system could save you in the long run, answer a few quick questions below and we'll generate an estimate.

1. Save money on charging

You’ll save around £400 per year on charging costs by getting electricity from your solar panels instead of the grid, on average.

This saving rises to £770 when you compare it to using public charging stations, which typically charge a significant premium.

And just in case you were still wondering whether you should switch to an EV, it’s around £1,000 cheaper to run a car on your own solar electricity rather than petrol.

2. Maximise your savings with smart tariffs

If you use a smart tariff like Intelligent Octopus Go, you can save as much as possible, reaching and even exceeding the figures mentioned above.

You can use the app to set how much charge you need and when you need it, and Octopus will automatically charge your car when it’s cheapest.

This may mean using the solar electricity your panels generate, or if it’s nighttime and you don’t have a battery, the charger may use grid electricity – but for just 7p per kWh (kilowatt-hour).

Some other energy suppliers offer EV tariffs with a cheap off-peak rate that means you can save by charging your car at a specific time of the day – which is much less flexible.

3. Cut your carbon footprint

With the sun powering the great majority of your driving, you’ll typically save 248kg of CO2 per year, in addition to the 1.5 tonnes you save by driving an EV instead of a petrol car.

Electricity from the national grid is much greener than it used to be, but still emits 149g of CO2 per kWh.

The average EV owner requires 2,029kWh to power their annual driving distance of 6,600 miles, around 82% of which can typically be supplied with solar panels, according to our calculations.

Due to seasonal variations in daylight hours, the remaining 18% will typically be supplied by the grid.

Your solar panels will still likely produce excess electricity during the summer and spring, which you can use at home or sell to the grid, reducing your carbon footprint even further.

4. Protect yourself against energy price rises

Solar panels enable you to cut your reliance on the electricity grid.

This softens the blow of any price cap rises, as your EV charging needs can mostly be fulfilled by your solar panels.

For example, if the price of electricity rose by 10%, this would naturally add 10% to your EV charging costs – but if you only rely on the grid for 18% of your car’s electricity every year, you’ll barely notice the difference.

As of October 2024, it’d work out to an increase of £9 per year, on average.

How many solar panels do you need to charge an electric car?

On average, you need six solar panels to charge an electric car – assuming each panel has a peak rating of 400W.

However, the average three-bedroom household that’s looking to power its appliances and charge an EV will need a 5.9kWp system, which is 14 solar panels at 400W each.

How much does it cost to charge an electric car with solar panels?

As a rough average, it costs £14,500 to install a solar panel system and home charging point.

First, you’ll typically need a 5.9kWp solar panel system, which usually costs around £11,500. If you add a solar battery, allowing you to store your solar electricity and use more of it to charge your car, the price tag rises by £2,000.

You’ll also need a home charger, as you can’t efficiently use solar electricity to power your car without one. These generally cost around £1,000, for an overall cost of £14,500.

These figures are estimates, and the prices you pay will depend on multiple factors, including each product’s brand and capacity, your location, and which installer you hire.

The average EV needs 2,029kWh per year, which this system will produce – and thanks to the solar battery, you’ll be able to use it whether your car is home during the day or not.

However, due to seasonal variations in the amount of light that hits your solar panels, this supply of solar electricity isn’t consistent.

You’ll therefore need to import around half of your electricity from the grid in winter, plus a small amount during autumn, according to our calculations.

However, in the spring and summer you’ll typically generate more than you need in order to charge your EV, which you can use in your home, cutting your electricity bills further.

This means even if you already have a home charger, solar panels will still save you hundreds of pounds per year on your electricity bills.

If you don’t already own a home charger, and use public chargers to top up your car’s battery instead, this setup will typically save you £770 per year.

To find out how much a solar & battery system could save you in the long run, answer a few quick questions below and we'll generate an estimate.

When is the best time to charge an electric car with solar panels?

The best time to charge an electric car with electricity from your solar panels is around the middle of the day, when the sun is highest in the sky and your system is generating the most energy.

This is often the point when your panels are generating more electricity than you can use, so instead of sending it to the grid through one of the best export tariffs, you can use it to charge your car.

However, if you have a solar battery, you can store this electricity to use in the evening or night, meaning your car doesn’t have to be home during the day to be charged.

If you’re on a smart charging tariff like Intelligent Octopus Go and you need to top-up your car’s battery further, you can then charge your car from the national grid for just 7p per kWh, any time between 11:30pm and 5:30am.

How long does it take?

It takes around six hours to charge the average electric vehicle from 20% to 80%, using a standard 7kW charger.

It’s usually best to charge your car to no more than 80%, both to lengthen your battery’s lifespan and because it takes roughly the same amount of time to charge up to 80% as it does to charge from 80% to 100%.

You can absolutely charge your car to 100%, but it’ll degrade the battery slightly every time you do, so it’s best to only do so before a long trip. When you do so, it’ll take around 10 hours.

There’s also no harm in discharging your electric vehicle below 20% – as long as you don’t leave it that way for weeks or months – but it’s always safer to have some electricity left in your battery, just in case.

If you’re using a solar charger, it’ll automatically charge your car’s battery when your solar panels are generating electricity, and use grid electricity the rest of the time – but more slowly.

This means it could take longer to charge your car, especially during winter when your panels are less productive.

Charging in the summer vs winter

Since we have seasons in the UK, the amount of daylight hours varies across the year – which means your solar panels will generate more in some months than others.

That means you’ll need to use more grid electricity to charge your car during the winter months, when the days are shorter and the skies are cloudier.

On the flip side, your panels will usually generate more electricity than you can use in summer, which means you can massively cut your EV charging bills and sell the excess to the grid with a solar export tariff.

You can see this generation pattern in the output chart below, which is based on a four-bedroom home in Essex with a 6kWp solar panel system and 5kWh battery. The system produces almost 25kWh of electricity per day in May and July, but just 4.9kWh each day in December.

Next steps

You now have all the information you need to decide whether or not you want to use solar panels to cut hundreds of pounds off your annual EV charging costs.

All that’s left is to choose a solar panel system – and ideally, a solar-compatible EV charger to go with it.

If you’re wondering how much a solar & battery system could save you, just answer a few questions below, and we’ll provide you with an estimate.

Charging an EV with solar: FAQs